26 



THE MODERN PEACH PRUNER. 



which is absolutely required for carrying on their 

 functions. 



A main drain, at least 4 feet deep, running 

 under the walks, and connected with this border 

 at intervals, is requisite, unless in the case of stony 

 subsoils. It is hardly known how much drainage, 

 well carried out, increases the temperature of the 

 borders. Whatever tends to increase the tempe- 

 rature of the soil, in naturally cold and damp 

 countries, is of the highest importance. Continental 

 writers are not so explicit on this point, but possibly 

 the amount of evaporation lessens the danger. 

 Of late years this subject has gained ground even 

 among them. 



Silex, or sand, is found more or less in all soils. 

 Sands vary much in colour. Sand more unequally 

 reduced forms gravel ; when flinty, it is termed 

 silicious ; with mica, micaceous ; when very fine, 

 dust. Silica allows w r ater to evaporate from it 

 twice as fast as chalk, and three times as fast as 

 clay. Sandy soils are early, and wrought easily, 

 but are incapable of great production. They are 

 " hungry soils," and in them manures soon dis- 

 appear : these should, therefore, be applied only 

 for the crop of the current year. Silicious soils 

 vary in colour from white to red, according to the 

 quantity of oxide of iron which they contain. 

 They are friable and penetrable to a great extent 



